THE TWO BASIC MEASUREMENTS FOR THE CONTROL OF DOMESTIC SEWAGE

Basically, there are two ways in which engineers measure the effectiveness of domestic sewage systems. The first is the measurement of the solids that are suspended in the system effluent. The second is the biochemical oxygen demand (BOD). This is a lab test that measures the uptake of oxygen by the effluent sample. Oxygen must be present to suport the biological action that naturally purifies the sewage. In natural surroundings normal purificaiton takes place as oxygen is dissolved into water as a stream flows over rocks, or by wave action on a lake or by oxygen contact with the surface of a pond. The more oxygen available to the sewage, the faster and more complete the purification process becomes. It is this principle --the accelerated introduction of oxygen and fixed biological growth -- that makes the Five Star RBC package plant such an effective sewage processing system.

THE ROTATING BIOLOGICAL CONTACTOR PROCESS:

The first compartment; this is the on-board septic (Tank) zone, the primary settlement tank or clirifer. Sewage enters here and separation of solids begins with heavier materials settling to the bottom. Floating solids remain on the inlet side with the RBC unit acting as a weir and grease trap.

The scond compartment is the RBC unit: it has four zones. The first zone has a lot in the bottom so that spent solids, which naturally fall from the disks, are allowed to settle to the sludge storage at the bottom of the primary tank. It also has an ilet slot near the affluent surface. The rotation of the disks causes a natural pumping action through the zone inlet and out the bottom slot. This ensures that his zone always has an abundant supply of organic matter, and the biological build-up during no-flow conditions is drastically extended.

Each of the four zones has a rotating disk pack and are designed so that the flow through each section maximizes the contact between sewage and the rotating disks. The disks turn at very low rpm achieving maximum biological build-up, which permits the micro-organisms, naturally present in domestic wastes, to multiply and grow to an optimum thinkness by alternate immersion in the sewage and the atmosphere. These micro-organisms then feed on the organic matter.

Attached to the fourth zone's disk is a recirculation scoop that dumps water onto a splash plate with each rotation. This water splashes into the primary tank and provides denitrification.